(1) FIELD OF THE INVENTION
The present invention relates to lights having a wide angle radiation pattern and particularly to lights for public safety vehicle use. More specifically, this invention is directed to compound parabolic reflectors which direct light emitted by a single source in a plurality of directions and especially to multiple cooperating integral reflectors for use with multiple light sources of diverse types. Accordingly, the general objects of the present invention are to provide novel and improved devices of such character.
(2) DESCRIPTION OF THE PRIOR ART
Warning light systems intended for employment on emergency vehicles, such as police cars, ambulances, fire trucks and the like, are typically required to emit bursts of light which are readily visible from all sides of the vehicle. The warning lights of such systems may comprise a rotating or oscillating incandescent lamp assembly, a moving mirror and cooperating lamp or a stationary light source and cooperating fixed position lens and reflector. The prior art warning lights can be relatively expensive to manufacture. Additional drawbacks of many prior art warning lights are poor volumetric efficiency, high wind resistance, the inability to simultaneously employ diverse types of light generator and the inability to aim light generated by a single source in plural directions.
A number of improved lights having particular applicability to emergency vehicle warning light systems have recently been introduced. Many such lights employ xenon flash tubes and have found wide popularity. For example, U.S. Pat. No. 4,792,717, which is assigned to the assignee of the present invention, discloses a compact wide-angle warning light. This warning light employs a unique reflector with multiple reflective surfaces, a lens and a light emitter in the form of a specially designed xenon flash-tube. The reflector comprises a parabolic linear section disposed between parabolic dish end sections.
U.S. Pat. No. 4,954,938, which is also assigned to the assignee of the present invention, discloses a novel single emitter light assembly comprising a compound reflector and a lens which is mounted to and covers the reflector. The reflector includes a first parabolic dish-like reflective surface which forms a surface of revolution about a central axis. A light emitter mounting base projects from the first reflective surface and accepts a light emitter such as a halogen lamp or a gaseous discharge tube. The central axis extends through the emitter mounting base. A pair of reflector wings are located at equidistantly-spaced diametral positions from the central axis. The wings each define a parabolic reflector surface which has its axis canted in relation to the first reflector surface, i.e., the surfaces from which light is reflected are defined by three parabolas and these three parabolas have, to the extent manufacturing tolerances permit, a common focal point. The lens preferably includes a multiplicity of light spreaders, typically optical refracting ribs, which project interiorly from the lens surfaces. A pair of recesses are formed in the interior of the lens for mating with the outwardly disposed shoulder portions of the wings so as to mount the lens to the reflector and to angularly fix the orientation of the axes of the spreaders relative to the reflector. A source of radiation, optionally in the form of a halogen lamp or a gas discharge tube, is positioned in the envelope between the lens and the reflector at the common focal point of the reflector defined parabolas and produces a generally uni-directional, wide angle beam pattern which radiates through the lens.